| The Low Energy Beam and Ion Trap (LEBIT) facility at the NSCL converts the beam of rare isotope ions produced at relativistic energies by in-flight separation of heavy projectile fragments into a low energy beam. To achieve this, gas stopping and advanced beam manipulation techniques are used. The facility's first experimental apparatus is a 9.4 T Penning trap mass spectrometer for performing high-precision mass measurements on short-lived isotopes. Within this work important components of the LEBIT facility have been developed and a series of high precision mass measurements performed.;Mass measurements of 63,64Ga, 64,65,66Ge 66,67,68As and 69Se at the LEBIT facility at the NSCL by Penning trap mass spectrometry have been performed within this work. Masses of the N=Z nuclei 66As and 64Ge have been determined with uncertainties of 8 deltam/m = 5x10-7 and 6x10-8, respectively, representing a more than 10-fold improvement in precision over previous measurements. For 63,64 Ga, 65,66Ge, 67,68As and 69Se relative mass uncertainties of deltam/m < 5x10-8 have been obtained. 69Se is found to be 135 keV more bound than the value listed in the 2003 Atomic Mass Evaluation. Using theoretical Coulomb shift energies in combination with the experimental mass values, improved mass predictions for 63Ge, 64,65As, 66,67Se and 68,69Br have been made. These predicted mass values, in conjunction with the experimentally determined mass values, are used to calculate improved effective lifetimes of the rp-process waiting point nuclei 64Ge and 68Se. It is shown that 64Ge is less of a waiting point while 68Se poses a larger delay in the rp-process than previously thought. The more precise mass values now available in this region are also used to investigate the neutron-proton pairing energy of odd-odd N=Z nuclei. |
